The present invention relates to a liquid crystal indicator for those products, such as washing machines, which are used in highly moist places.
Because of wide availability and legibility (or easiness to see) of displayed information, liquid crystal indicators are currently used in many types of products such as word processors, TV units, OA (Office Automation) equipment, cameras, clocks/watches as well as automobiles. The application fields and the quantity of those indicators used are continuing to increase rapidly. Liquid crystal indicators also have received attention in the home electric appliance industry producing a variety of products, and are beginning to be adopted in part of the products. However, it has been generally thought difficult to adopt such indicators in products employed under moist conditions, since liquid crystal display sections inclusive of backlights are susceptible to moisture.
While liquid crystal indicators have been recently incorporated in the above type products with some anti-moisture treatment as required, in some cases perfect satisfaction cannot yet be attained with respect to anti-moisture structure, assembling efficiency, etc. Looking briefly at the structure of incorporating liquid crystal indicators in electronic rice cookers, motorcycles or the like which are used in environments exposed to steam or rain, for example, a liquid crystal alone or a liquid crystal with a backlight is directly mounted onto a product control substrate, followed by placing this assembly in a container and enclosing it with a cover. A packing made of rubber or the like is applied to a joint region between the container and the cover, and is then held tight by fastening a number of screws to maintain a sealed condition. Further, in anticipation of the situation wherein a cable line leading from the control substrate is moved around very frequently, an outlet of the cable line is sealed off by applying elastic silicone rubber for injection molding or the like thereto. In some cases, aiming at perfect removal of moisture, desiccants are put in the container accommodating the liquid crystal display section.
However, the above prior art has difficulties in maintaining the inside of the container in a sealed condition because of variations in smoothness of the joint surfaces between the container and the cover, or in the process of applying the silicone rubber to the cable outlet. In addition, with air filled in the container, the air volume is changed due to differences in the ambient temperature, which causes the breathing or respiration through holes in walls of the container, small gaps at the joint surfaces between the container and the cover, or air bubbles in the applied silicone rubber. This allows moisture to enter the container and prevents lasting of a perfectly sealed condition. Consequently, the prior art is not sufficiently suitable for use in those products, such as washing machines, which are employed in extremely watery and moist places.